Flap opening size is 8.25" W x 10.4" H, For SMALL dogs and cats. AUTOMATIC CLOSE & LOCKABLE - Dog door with magnetic flap closures keep the door closed after your pet leaves. SUITABLE FOR ALL DOORS - Includes sliding doors, glass door windows, panels and patio or any other screen areas. Allow your pets freedom to get in and out. DURABLE - This pet door frame is made of high quality ABS material. The mesh yarn is made of high grade materials and is strong and durable. EASY TO INSTALL - Just need to install it with screws according to the instructions.